In the positioning control of a linear motor, a linear scale is used to increase a positioning accuracy. However, when a mover of the linear motor has a long range of motion, it is necessary to increase the length of the linear scale. In addition, it is also necessary to use a linear scale having less distortion. Therefore, the manufacturing cost of the linear motor is increased.
Accordingly, a linear scale is only mounted in a range of motion in which positioning control is needed, so that the manufacturing cost is reduced (Patent Literature 1).
In addition, the magnetism of a drive magnet of a linear motor is detected using an MR sensor attached to a mover and a position of the mover is calculated from the detected magnetic strength to perform the positioning control.